Various Questions Regarding Video Playback...


May 1, 2003
Posted this on the GPX2 website, I was hoping that you guys can answer my questions if you know the answers:


I'm surprised these questions haven't been asked but...

1. In the specs, it was stated that the GPX2 can handle video up to 720x480 at 30 FPS with a video bitrate of 1178 Kbps. Does this apply to all the video codecs (Divx, Xvid, WMV, etc...) or just some of them? If only some, what are the highest values for each codec, and can we expect playback to be at 30 FPS also?

2. Are extended features of codecs supported on the GPX2, such as b-frames and global motion compensation (GMC)?

3. What resizing method will be used on the videos, bilinear, bicubic, or nearest neighbor?

4. With the TV-Out accessory that will be available for purchase, will it only have composite out or will S-Video/Component out be supported? Any chance of getting a VGA-Out also?

And one request...

Please do not make the GPX2 video playback like the Creative Zen Vision. That device purports that it supports Divx and Xvid but what it really does is that software resizes your videos down to 320x240 and compresses them to WMV with a maximum video bitrate of 885 kbps. After it's recompressed, it then gets loaded onto your player.

For ages, I've been looking at a device that could do perfect SNES emulation as well as double as a MP3 player and video playback where I could just drop the file on my computer onto a card and play it on the go without having to recompress anything. I have high hopes that the GPX2 might be it.
there really is no answer for these questions just yet, at least until we can get our hands on one. Earliest opportunity will be next month at the GBAX pre release party.
i'd imagine the bitrate issue relates to the bandwidth at which the card can be read so it's likely to be pretty much the same for all codecs. I'd imagine the codecs are linux compatible versions with WMV/QT/Real alternative codecs used for those types of vids so it's likely to support whatever features are already implemented under linux although anything that uses hardware acceleration (do they need opengl in linux?) would have to be coded

the 2d cpu is used in dvd players so id consider it very likely it can do full 30fps.
at #4:
The guy from gp32z has confirmed that it will be s-video (only I guess)

Concerning your request, I guess that is a sure bet... just put the files on the gpx2 and watch. But maybe a few obscure codecs and bitrates will not be suported.

P.s.: Perfect SNES could be possible, but we don't know for sure yet.
S-TV is fine...

I have s-tv to component adapters lyin around my room somewhere.

actually even better if I buy a TV-in tuner for my comp with S-tv input.
Honestly guys i hear allot of people saying perfect snes or gba emulation is still in the limbo. Honestly if i dont see ATLEAST perfect SNES emulation i will not spend 200 dollers on the system. I really dont expect gba to be compat but if they get one of the processors to run the GPU then mabe its possible. I was confused at what dual processors meant. I thought that a dual processor used BOTH as one. But it appears that as everyone says in this board that one processor handles one process. I really dont know how it works can anyone explain? I wouldve thought that they could combine 2 processors to run the same program but one processor is a video host so i really dont know. I want A DEVELOPER to please clerify this for us. Im sick of people answering questions when there not even in the developer game.
Honestly if i dont see ATLEAST perfect SNES emulation i will not spend 200 dollers on the system
Technically, nothing should be taken for granted on this system. However, logically, perfect SNES emulation (perfect being sound on and 0 or 1 frameskip -- compatibility is the original project's job) is VERY likely -- especially since there are two processors; one can handle the audio and video chipsets, the second handles the actual processor.

The GBA is a more advanced system than the SNES. GBA emulation is positive to show up for the GPX2 -- because it has on the GP32. But GBA emulation on the GP32 is abysmal. Hopes are much higher for the GPX2. In my opinion, GBA emulation should easily run half speed.

I really dont know how it works can anyone explain?
The previous comment should help you out, but think of it this way: on most modern computer systems, the main processor (AMD Athlon, Intel P4, w/e) handles most of the load. Then, there is a second processor on a graphics card (Radeon, NVidia, etc.) that handles the video. You may well be aware that playing taxing games, even with a fast main preocessor, can be very difficult without a graphics processor (as well as a bunch of RAM). When you say processes, I hear threads. In general, multiple cores or similar processors handle different threads of the OS, not a main processor and gfx processor combination.

...but one processor is a video host so i really dont know.
If you're worried about smooth playback simply because the video playback may be loaded onto the graphics processor, you shouldn't be. The purported 200mHz of the co-processor is more than enough to playback full motion video. Even if it's not 200mHz, remember -- Gamepark Holdings is marketing this as a multimedia device, not some low-quality gaming handheld.

I am a developer and acknowledged of many console systems and their emulation. However, I am not yet a GP32 or GPX2 developer. Take my predictions with a grain of salt, but overall they should be rather spot-on.

To break it down real quick, and I hope every goddamn newbie on this site reads this so I never have to explain it again, there's a hardware video decoder inside the GPX2, as well as a general purpose second processor.

The main proc is an ARM920T, wich is the exact same core as in the gp32, running at 200mhz. It has a buddy, an ARM940T wich is basically the same thing, but without MMU (needed for multitasking and running an OS, wich is why imho it will be unlikely that these two cores will work as a dual core system like a dual processor PC) and less cache. Running code on the coprocessor (the 940T) will hopefully be possible. If that's the case, full framerate SNES emulation with sound shouldn't be a problem.

"MP2520F’s Video Processor can support multiple standard video codec functionality including MPEG4, DivX
3.11/4.x/5.x and JPEG standard. The Video Processor consists of multiple macro-functional H/W blocks including
VLD/VLC, DCT/IDCT, Q/IQ, ME, MP, MC, De-Block, De-Ring and SP(stream packet processor)."

So movies are decoded by dedicated hardware. This is why they can get such a high resolution and framerate on a mere 200mhz dualcore machine. There's also a video post processor:

"MP2520F’s Video Post Processor consists of multiple macro-functional H/W blocks including a video signal scaling
block and OSD, sub picture, hardware cursor, hue control, contrast, brightness, dithering, gamma, alpha blending, color
key and CSC(color space converting) blocks."

So scaling the picture down is done in hardware. I can't find a reference on how this is done though.

Hope this clears up a few things.